Rotation Angle Detector Yoke Segmentation for Flux Uniformity
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Solution Overview
Problem
Conventional rotation angle detectors face challenges with accuracy due to disturbance magnetic fields and complex magnet shapes, leading to increased manufacturing costs and reduced robustness.
Innovation Solution
A rotation angle detector design featuring a frame-shaped magnetic-flux-transmitting means with a symmetrically disposed magnetic-field-generating means and a magnetism-detection means, which enhances magnetic flux uniformity and robustness by shielding against disturbances and simplifying configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a yoke is circumferentially provided around the Hall elements to shield against disturbance magnetic fields, then the accuracy is improved, but the magnetic flux vector becomes curved due to leakage magnetic flux, reducing robustness
Solution Approach 1:
The yoke is segmented into a first yoke portion and a second yoke portion positioned at different radial distances from the rotation axis. This segmentation allows each portion to handle different aspects of magnetic flux, preventing the flux vector curvature that occurs in a single circumferential yoke while still providing disturbance shielding.
Solution Approach 2:
The invention transitions from a single-plane circumferential yoke arrangement to a multi-dimensional arrangement with yoke portions at different radial positions. This dimensional change enables the magnetic flux to be guided more effectively without becoming curved, maintaining both accuracy and robustness.
2Reliability
If two magnets with curved surfaces are arranged to confront with each other through a magnetic detecting element to uniform magnetic flux, then robustness is improved, but the shape of the magnet becomes complicated, increasing manufacturing cost
Solution Approach 1:
Instead of using complex curved magnet surfaces, the invention uses a simple planar yoke structure that copies or replicates the flux-uniforming effect through its geometric arrangement. The first and second yoke portions at different radial positions serve as a simplified counterpart to the complex curved surface design.
Solution Approach 2:
The invention replaces the mechanical complexity of curved magnet surfaces with a simpler yoke-based magnetic circuit design. The flux uniforming is achieved through the yoke's geometric configuration rather than through complex magnet shaping, reducing manufacturing difficulty.
3Ease of manufacture
If no yoke is provided around the magnetic-field-measuring element to simplify configuration, then manufacturing is easier, but the accuracy is deteriorated by disturbance magnetic field
Solution Approach 1:
The yoke is divided into two distinct portions at different radial positions, allowing the structure to provide effective disturbance shielding while maintaining relative configuration simplicity. Each portion serves a specific function in managing the magnetic flux and shielding against disturbances.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution improves the balance and uniformity of the magnetic flux, enhancing the robustness and accuracy of the rotation angle detection while reducing manufacturing complexity and costs.
Implementation Method 1
The magnetic-flux-transmitting means is comprised of a first wall, a second wall, a third wall and a fourth wall which are made of magnetic material
Implementation Method 2
The magnetic-field-generating means is disposed on only an inner surface of the first wall and is magnetized in a direction orthogonal to the first wall
Implementation Method 3
The magnetism-detection means having a detection surface which detects a magnetic flux
Data Source
AI summary
A rotation angle detector is provided with a frame-shaped yoke which includes a first wall and a second wall in parallel. A rotation axis of a detection subject extends inside of the frame-shaped yoke. A magnetic flux vector is uniformed in a direction orthogonal to the first wall, whereby even if a position of a Hall element deviates, the detected magnetic flux density is less varied. A robustness of the detector is enhanced. A distance between the Hall element and a second inner surface of the second wall is shorter than that between the Hall element and a first inner surface of the first wall. A length of the second inner surface is longer than a length of the first inner surface. At a vicinity of the second wall, the area in which the magnetic flux vector is uniformed can be enlarged. Thus, the robustness is further enhanced.